Gas sample tube



Oct. 31, 1961 w. E. GREENE ETAL GAS SAMPLE TUBE 2 Sheets-Sheet 2 Filed March 3, 1958 Jim: 6.

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United States Patent 3,006,194 GAS SAMPLE TUBE William E. Greene, Pasadena, and Alfred D. Robinson, El Monte, Calif., assignors, by mesne assignments, to I Beckman Instruments, Inc., Fullerton, Califi, a corporation of California Filed Mar. 3, 1958, Ser. No. 718,541 20 Claims. (Cl. 73421.5)

This invention relates to gas sample tubes suitable for use in furnaces and the like where it is desired to take samples of gases resulting from the combustion process. The invention is particularly related to a sample tube for use where a large quantity of solid particles is found in the gas from which the sample is being drawn.

Accordingly, it is an object of the invention to provide a gas sample tube suitable for insertion into a gas flow path for withdrawing a gas sample therefrom with the tube having a magnetized structure for removing magnetic particles from the sample. A further object of the invention is to provide such a gas sample tube for use in combination with a wetting spray which wets solid particles and carries them out of the gas stream when the liquid and gas are separated. Another object of the invention is to provide such a gas sample tube in which a fluid, either liquid or gas, may be directed through the tube counter to the gas sample flow for flushing the solid particles out of the tube. Another object of the invention is to provide such a structure in which the flushing fluid may either be the wetting spray or may be furnished from a separate source.

It is a further object of the invention to provide a gas sample tube having magnet means positioned within the tube and an apertured structure disposed within the magnetic field providing a large surface area for attraction of solid particles in the gas sample passing therethrough. Another object of the invention is to provide such a gas sample tube suitable for use with one or more permanent magnets or electromagnets. A further object of the invention is to provide such a structure in which the electromagnet may be either A.C. or DC. and may be operated continuously or may be interrupted periodically providing improved flushing operation. A further object of the invention is to provide such a structure in which the flushing operation may be carried out continuously or periodically.

Gas sample tubes are often provided with cooling jackets to prevent damage to the tube when inserted into the hot gases of a furnace and it is an object of the invention to provide a gas sample tube which can be inserted into a cooling jacket and one which can be permanently built with a cooling jacket. A further object of the invention is to provide a novel type of cooling jacket having the wetting spray nozzle carried at the end of the jacket.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. The drawings merely show and the description merely describes preferred embodiments of the present invention which are given by way of illustration or example.

In the drawings:

FIG. 1 shows a preferred embodiment of the invention mounted in a wall of the furnace;

FIG. 2 is an enlarged view of the right-hand end of FIG. 1;

FIG. 3 is a sectional view taken along the line 33 of FIG. 2;

FIG. 4 is a partial sectional view of an alternative embodiment of the invention;

3,006,194 Patented Oct. 31, 1961 FIG. 5 is a sectional view taken along the line 5--5 of FIG. 4;

FIG. 6 is a partial sectional view of another alternative embodiment of the invention;

FIG. 7 is a sectional view taken along the line 77 of FIG. 6;

FIG. 8 is a partial sectional view of another alternative embodiment of the invention;

FIG. 9 is a sectional view taken along the line 99 of FIG. 8;

FIG. 10 is a partial sectional view of another alternative embodiment of the invention;

FIG. 11 is an end view taken along the line 11-11 of FIG. 10 with the cooling jacket shown in phantom; and

FIG. 12 is a diagram illustrating the operation of the embodiment of FIG. 4.

In the embodiment of the invention shown in FIGS. 1, 2 and 3, a cooling jacket 15 is projected into a furnace through an opening 16 in a furnace wall 17, a mounting flange 18 carried on the exterior of the Wall providing support for the cooling jacket. The cooling jacket 15 includes concentric tubes 21, 22 joined at one end by a plate 23 and at the other end by a plug 24 with a fluid inlet pipe 25 and a fluid outlet pipe 26 providing for circulation of a cooling fluid through the cooling jacket.

A tubular member 29 carrying a magnetic unit 30 and a wetting spray nozzle 31 is slidingly positioned within the cooling jacket. A cap "32 which is threadedly engageable with the plug 24 and a fitting 33 fixed to the end of the tubular member 29 supports the tubular member relative to the cooling jacket.

A tube 34 is positioned within the tubular member 29 with one end fixed in the fitting 33 and the other end flared to engage the tubular member 29 and apertured to provide the nozzle 31. It is preferred to connect a vacuum pump or the like to the projecting end of the tube 34 via pipe coupling 35 for drawing a gas sample from the furnace into the tubular member 29, past the magnetic unit 30, and through the tube 34. A stream of liquid, such as water, may be coupled to the fitting 33 through pipe coupling 36 for spraying from the nozzle 31 to wet particles and remove them from the gas sample. This wetting spray will run out the open end of the sample tube and prevent clogging by ash and the like.

The magnetic unit 30 includes tubes 39, 40, 41 concentrically positioned within the tubular member 29 with permanent magnets 42, 43, 44, 45, 46 positioned between and supported by the tubes 39, 40, 41. These tubes preferably are thin walled and dimensioned so that they will be deformed slightly by the magnets for securely positioning the magnets, as best seen in FIG. 3. The tubes may be solid or may be formed of wire screen or similar apertured material.

The magnets 42-46 are spaced slightly from each other with their opposite poles adjacent, i.e., the north pole of 42 is adjacent the south pole of 43. The magnetic unit produces widespread magnetic lines of force throughout the tubular member through which the gas sample must pass. The tubes 39, 40, 41 which support the magnets also provide additional surface are for the magnetic particles in the sample gas to adhere to. These tubes may be made of nonmagnetic material, but it is preferred when the magnets are strong enough to saturate the tubes and still give lines of force in the intermediate spaces, to make the tubes of magnetic material. The number of magnets used, the strength of the magnet, and the relative dimensions of the various components are dependent upon the particular application of the apparatus. When a continuous wetting spray is being utilized, it is not necessary that the magnetic unit attract all of the magnetic particles to a surface but merely that the motion of the magnetic particles be retarded sufliciently to permit them to be wetted by the spray and carried out of the gas stream.

The structure of FIGS. 1, 2 and 3 permits various methods of flushing the particles from the magnetic unit. A continuous or a periodic stream of fluid, such as the wetting spray, may be projected from the nozzle 31 to flush out the magnetic unit. Alternatively, the drawing of the gas sample may be periodically interrupted and a fluid either liquid or gas, such as compressed air, may be projected through the tube 34 for flushing the magnetic unit.

In a gas sample tube built according to the teaching of FIGS 1, 2, and 3 for use in an open hearth furnace with an oxygen lance, five magnets three sixteenths inch in diameter and one inch long were supported in a one inch tubular pipe by three thin walled nonmagnetic tubes each one quarter inch in diameter. A continuous wetting spray from the nozzle was used to back wash the particles out of the tube.

The embodiment of the invention shown in FIGS. 4 and 5 utilizes a cooling jacket 49 similar to the cooling jacket 15 of the embodiment of FIG. 1. The righthand end of an inner concentric tube 50 is flared to engage the corresponding end of an outer concentric tube 51, this flared end being apertured to provide a spray nozzle 52. The fluid which flows through the cooling jacket may also be projected from the spray nozzle if desired. However, it is preferred to use a separate source for the spray fluid because industrial water suitable for cooling purposes frequently contains so much foreign matter that small passages in the nozzles are rapidly plugged. Ordinarily, filtered water is used for the wetting spray. When separate sources are used for the cooling and spraying, a ring 53 is fixed between the concentric tubes between the nozzle 52 and an outlet pipe 54 to block flow of cooling fluid to the nozzle. A spray liquid supply pipe 55 may be positioned between the concentric tubes 49, 50 with one end passing through the ring 53 and the other end passing outward through the tube 49 in the same manner as the fluid inlet pipe 25 of FIG. 1.

A tubular member 58 for withdrawing the gas sample in the same manner as the tubular member 29 of the embodiment of FIG. 1 is slidingly positioned within the cooling jacket 49. The magnetic unit 30 of FIG. 2 may be positioned within the tubular member 58 or another magnetic unit 59 may be utilized. Permanent magnets 60, 61, 62 are fixed in spaced relationship in a tube 63 by spacers 64, 65, 66, 67. The tube 63 is supported within the tubular member 58 by transverse screens 68, 69, 70, 71 which are held in position by spacers 72, 73, 74, 75, 76.

In this embodiment, the magnets are positioned with like poles adjacent each other, i.e., the north poles of 60 and 61 are adjacent and the south poles of 61 and 62 are adjacent. The screens 68-71 and the spacers 73, 74, 75 or the tubular member 58 or both are preferably made of magnetic material to provide strong magnetic fields in the gas passages. Apertured discs or similar structures providing support for the tube 63 while permitting passage of gas therethrough may be substituted for the screens 68-71 if desired.

In the embodiment of FIGS. 4 and 5, the flushing fluid is preferably supplied periodically by disconnecting the sample gas withdrawing apparatus from the tubular member 58 and connecting the flushing fluid source thereto, as shown in FIG. 12.

The embodiment of FIGS. 6 and 7 utilizes the same cooling jacket 49 as the embodiment of FIGS. 4 and 5. However, in this embodiment, the inner tube 50 of the cooling jacket serves as the duct for withdrawing the gas sample, the gas sample tube being a unitary structure.

The magnetic unit of FIG. 2 or of FIG. 4 may be utilized within the tube 50 if desired. In the alternative form shown in FIGS. 6 and 7, an electromagnet 81 is mounted in the tube 50 and transverse screens 82, 83, 84 are mounted in a tube 85 with spacers 86, -87, 88, 89, the tube 85 in turn being mounted within the electromagnet 81. The screens are preferably made of magnetic material producing regions of relatively high field strength at the openings in the screens for attracting the particles in the gas stream passing therethrough. The tube 50, the tube 85 and the spacers 86-89 are preferably of nonmagnetic material so as to concentrate maximum field strength in the magnetic screens.

When an electromagnet is used in the magnetic unit of the gas sample tube of the invention, the magnetic field strength is easily adjusted to provide optimum performance of the device. Also, the magnet may be deenergized during the flushing period thereby improving the flushing operation. Where a continuous water spray is used, as in the structure of FIGS. 1 and 2, an A.C. magnetic field will be as effective as a DC. field, since the particles in the sample gas will be retarded enough for the spray water to wet them, which essentially separates them from the gas stream resulting in their being flushed out of the tube.

A modification of the magnetic unit of FIGS. 6 and 7 is shown in FIGS. 8 and 9. The tube 85 is positioned within the tube 50 by end rings 94, with the magnet 81 either mounted on the tube 85 or in the tube 50. Four apertured structures 96, 97, 98, 99 are positioned in spaced relationship Within the tube 85 and magnet 81, the four structures being identical. Each of these structures consists of seven short lengths of thin walled magnetic tubing, best seen in FIG. 9. The operation of this magnetic unit will be the same as that of FIG. 6, with each of the short tubes having a region of high magnetic field at each end. This particular embodiment provides a very large surface area for the particles to adhere to and is especially suited for use with heavily loaded sample gas.

The embodiment of FIGS. 10 and 11 is similar to that of FIGS. 6 and 7, a horseshoe permanent magnet 100 being substituted for the electromagnet 81. In each of these embodiments, it is desirable to have the magnetic field of sufficient strength to saturate the screens, apertured discs, or tube assemblies. The number of screens, the strength of the magnetic field and the dimensions of the various components will of course be determined by the particular installation.

Although exemplary embodiments of the invention have been disclosed and discussed, it will be understood that other applications of the invention are possible and that the embodiments disclosed may be subjected to various changes, modifications and substitutions without necessarily departing from the spirit of the invention. In particular, it should be noted that the various methods of flushing and the various types of cooling jackets described may be used with any of the magnetic units, the invention not being limited to the particular combinations illustrated.

We claim as our invention:

1. In a gas sample tube for withdrawing a sample from a gas flow path, the combination of: a tubular member having an open end adapted to be positioned in the gas flow path; means for establishing a magnetic field within said tubular member; and means for directing a flushing fluid through said tubular member past said magnetic field and out said open end.

2. In a gas sample tube for withdrawing a sample from a gas flow path, the combination of: a tubular member having an open end adapted to be positioned in the gas flow path; means for establishing a magnetic fleld within a zone within said tubular member; a nozzle positioned in said tubular member for directing a fluid spray into said zone; and a conduit for conducting a fluid to said nozzle.

3. In a gas sample tube for withdrawing a sample from as gas flow path, the combination of: a tubular member having an open end adapted to be positioned in the gas flow path; means for establishing a magnetic field within said tubular member; a cooling jacket surrounding said tubular member adjacent said open end; means for flowing a fluid through said jacket; a nozzle carried on an end of said jacket for directing a fluid spray across said open end of said tubular member; and a conduit for conducting a fluid to said nozzle.

4. In a gas sample tube for withdrawing a sample from a gas flow path, the combination of: a tubular member having an open end adapted to be positioned in the gas flow path; means for establishing a magnetic field within said tubular member; a hollow cooling jacket surrounding said tubular member adjacent said open end, said tubular member being telescopingly removable from within said jacket; means for flowing a fluid through said jacket; a nozzle carried on an end of said jacket for directing a fluid spray across said open end of said tubular member; and a conduit positioned within said jacket for conducting a fluid to said nozzle.

- 5. In a gas sample tube for withdrawing a sample from a gas flow path, the combination of: a tubular member having an open end adapted to be positioned in the gas flow path and means adjacent the other end thereof for withdrawing a gas sample; means for establishing a magnetic field within said tubular member; a cooling jacket surrounding said tubular member adjacent said open end; and a nozzle carried on an end of said jacket for directing a fluid spray across said open end of said tubular member, said jacket including means for conducting a fluid to said nozzle.

6. In a gas sample tube for withdrawing a sample from a gas flow path, the combination of: a tubular member having an open end adapted to be positioned in the gas flow path; an apertured structure positioned within-said tubular member, said structure permitting fluid flow through said tubular member; means for establishing a magnetic field across the apertures of said structure; and means for directing a flushing fluid through said tubular member past said structure and out said open end.

7. In a gas sample tube for withdrawing a sample from a gas flow path, the combination of: a tubular member having an open end adapted to be positioned in the gas flow path; an apertured structure positioned within said tubular member and extending axially therealong, said structure permitting fluid flow through said tubular member; means for establishing at the apertures of said structure a plurality of approximately symmetrical magnetic fields axially disposed within said tubular member; and means for directing a flushing fluid through said tubular member past said structure and out said open end.

8. In a gas sample tube for withdrawing a sample from a gas flow path, the combination of: a tubular member having an open end adapted to be positioned in the gas flow path; permanent magnet means; and mounting means for supporting said permanent magnet means within said tubular member, said mounting means including a plurality of passages permitting fluid flow through said tubular member past said permanent magnet means.

9. In a gas sample tube for withdrawing a sample from a gas flow path, the combination of: a tubular member having an open end adapted to be positioned in the gas flow path; an annular electromagnet positioned within said tubular member; conduit means providing a plurality of fluid passages through said electromagnet permitting fluid flow along said tubular member; and means for directing a flushing fluid through said tubular member and said conduit means and out said open end.

10. In a sampling device for insertion into a gas flow path, the combination of: a tubular member for drawing a gas sample therethrough from the flow path; a plurality of permanent magnets, each of said permanent magnets having a north-south magnetic axis; means for mounting said permanent magnets within said tubular member with said axes in alignment and parallel to the axis of said tubular member and with said magnets spaced from each other; and means for directing flushing fluid through said tubular member past said magnets counter to the gas sample flow.

11. In a sampling device for insertion into a gas flow path, the combination of: a tubular member for drawing a gas sample therethrough from the flow path; a plurality of tubes mounted within said tubular member with the axes of said tubes parallel to and substantially equally spaced from the axis of said tubular member; a plurality of permanent magnets positioned between said tubes, each of said magnets having a north-south magnetic axis, said magnets being supported by said tubes with said magnetic axes aligned and parallel to the axis of said tubular member, said magnets being spaced from each other with opposite poles adjacent; and means for directing a flushing fluid through said tubular member past said magnets counter to the gas sample flow.

12. In a sampling device for insertion into a gas flow path, the combination of a tubular member for drawing a gas sample therethrough from the flow path; a plurality of permanent magnets, each of said magnets having a north-south magnetic axis; means for supporting said magnets within said tubular member with said magnetic axes in alignment and parallel to the axis of said tubular member, and with like poles of adjacent magnets facing each other creating a series of opposite poles along the axis of said tubular member, said means including a plurality of apertured discs of magnetic material transversely disposed within said tubular member, whereby the gas sample flows through said apertures, with a disc positioned at each pole of said series; and means for directing a flushing fluid through said tubular member past said discs counter to the gas sample flow.

13. In a sampling device for insertion into a gas flo-W path, the combination of: a tubular member for drawing a gas sample therethrough from the flow path; a magnet mounted within said tubular member for producing a magnetic field within a zone through which the gas sample passes; a plurality of apertured discs of magnetic material positioned within said zone transverse to the flow of the gas sample and spaced from each other; and means for directing a flushing fluid through said tubular member past said discs counter to the gas sample flow.

14. In a sampling device for insertion into a gas flow path, the combination of: a tubular member for drawing a gas sample therethrough from the flow path; a permanent magnet mounted within said tubular member for producing a magnetic field within a zone through which the gas sample passes; a plurality of screens of magnetic material positioned within said zone transverse to the flow of the gas sample and spaced from each other; and means for directing a flushing fluid through said tubular member past said screens counter tothe gas sample flow.

15. In a sampling device for insertion into a gas flow path, the combination of: a tubular member for drawing a gas sample therethrough from the flow path; an annular electromagnet mounted within said tubular member; a plurality of field structures mounted within said annular electromagnet for flow of the gas sample therethrough, said field structures being spaced from each other, each of said field structures comprising a plurality of short lengths of tubing joined together with their longitudinal axes parallel; and means for directing a flushing fluid through said tubular member past said field structures counter to the gas sample flow.

16. In a gas sample tube for withdrawing a sample from a gas flow path, the combination of: a tubular member having an open end adapted to be positioned in the gas flow path and means adjacent the other end thereof for withdrawing a gas sample; a cooling jacket surrounding said tubular member adjacent said open end; means for flowing a fluid through said jacket; a nozzle 7 r carried on an end of said jacket for directing a fluid spray across said open end of said tubular member; and a conduit for conducting a fluid to said nozzle.

17. In a gas sample tube for withdrawing a sample from a gas flow path, the combination of: a tubular member having an open end adapted to be positioned in the gas flow path; means for establishing a magnetic field within said tubular member; a hollow cooling jacket surrounding said tubular member adjacent said open end, said tubular member being telescopingly removable from within said jacket; means for flowing a fluid through said jacket; and means for directing a flushing fluid through said tubular member past said magnetic field and out said open end.

18; In a gas sample tube, the combination of: a first tubular member having an open end adapted to be positioned in the gas flow path for withdrawing a sample therefrom; means for establishing a magnetic field within said first tubular member; a second tubular member positioned concentric with said first tubular member for directing a flush .fluid through said first tubular member past said magnetic field and out said open end; a hollow cooling jacket positioned around said tubular members and extending to said open end; and a fluid inlet and a fluid outlet for flowing a fluid through said jacket.

19. In a gas sample tube, the combination of: a tubular member having an open end adapted to be positioned in a gas flow path; means for establishing a magnetic field withinsaid tubular member; a source of flushing fluid; a gas sample withdrawing apparatus; and means for selectively connecting said flushing fluid source and said sample withdrawing apparatus to said tubular member.

20. In a gas sample tube, the combination of: a tubular member having an open end adapted to be positioned in a gas flow path; means for establishing a magnetic field within said tubular member; a cooling jacket surrounding References Cited in the file of this patent UNITED STATES PATENTS M 1,957,209 Hedley May 1, 1934 2,356,845 Hines Aug. 29, 1944 2,685,205 Barnard Aug. 3, 1954 FOREIGN PATENTS 1,063,214- F-rance Dec. 16, 1953 

